An endocrinological study was performed dopaminergic regulation of the hypothalamic-pituitary axis of 3 patients with familial chorea-acanthocytosis (females, 38 to 47 years of age). All 3 patients exhibited low basal levels of triiodo-thyronine (T3), and 2 patients had a slightly elevated baseline plasma prolactin (PRL) level. The patients had a delayed plasma thyroid stimulating hormone (TSH) response and plasma PRL excessive response to thyrotropin releasing hormone (TRH), and a low plasma growth hormone releasing hormone (GRF) response to L-dopa. These TSH, PRL and GRF responses represent a secretion pattern due to a hypothalamic disorder, suggesting impaired regulation of hormone secretion by the dopaminergic system, primarily in the hypothalamus. In addition, an increased growth hormone (GH) response secretion following TRH (paradoxical response) was observed in 2 patients, suggesting that the pituitary was also involved. An oral glucose tolerance test (75g-OGTT) revealed a diabetic pattern in all 3 patients, indicating frequent association with impaired glucose tolerance.